Orthotic devices have traditionally been utilized to aid in support, guiding and limiting the range of motion of different joints in the human body. A mechanical joint is frequently used to pivotally connect two orthotic members secured to the body above and below the joint which members form part of the orthotic appliance, mounted on opposite ends such as for attachment to the foot, leg, arm, hand or neck of the body. Such a mechanical joint permits and controls relative movements of the members and the corresponding body parts to which the members are attached and the body joint to which the body parts are connected. Portions of orthotic devices have been constructed with thermoplastic resins or other materials and are conformed to the shape of an individual patient's anatomy. In a typical ankle-foot orthotic device, a plastic molded member of the orthotic device is conformed to the lower ankle and plantar region of the foot. This plastic member is pivotally connected to a second molded plastic member that is conformed to the shape of the rear lower leg and calf of the patient. These two members are connected pivotally at their sides adjacent to the ankle of the patient by use of mechanical joints to provide lateral support for the lower leg, ankle and foot of patients. This orthotic device permits pivotal movement of a desired part of the body through only a limited set range of flexion and extension.
One such prior art mechanical joint construction consists of a pivotably connected metal disc and plate disclosed in U.S. Pat. No. 4,738,252. The disc is provided with an arcuate slot radially spaced from the pivot point of the disc. A protrusion on the disc extends into the slot and moves there along to limit the relative rotation between the disc and the plate and the relative pivotal movement of the two members of the orthotic device. The orthotic device correspondingly limits the degree of flexion and extension of the foot relative to the lower leg of the patient.
A need exists for an orthotic device which can be easily adjustable to set the degree of pivotal movement permitted by the orthotic device about the orthotic joint thereof over a range without requiring additional orthotic device parts or changing parts to provide the desired degree of pivotal movement. A need also exists for such an orthotic joint that has few parts and is simple and economical in construction.